The Robo Retrofit House

Much is learned from a side-by-side study of a retrofit home and standard-built home.

A home built in the mixed-humid climate of Knoxville, Tennessee, with energy efficiency upgrades used 42% less energy than an identical standard built home in a side-by-side measured and modeled comparison. The two-story homes have three bedrooms, 21/2 baths, and 2,400 ft2 of living space. The house type, size, and dominant features were selected after a demographic housing study in the Tennessee Valley Authority (TVA) service territory determined that this was a typical house on the market from 2000 to 2008. The energy efficiency packages, all commercially available in the area, made a significant difference in energy use between the two houses. The Retrofit House has a HERS index of 68 (a HERS of 0 is a zero-energy house; a conventional new house would have a HERS rating of around 100). The identical Builder House next door has a HERS of 102.